org.mini2Dx.core.engine.interpolator

Interface Interpolator<T>

All Known Implementing Classes:

LinearCircleInterpolator, LinearPointInterpolator

public interface Interpolator<T>

The interpolation function for objects.

The initial value and current value are instantiated only once (on construction) to reduce object allocation.

   // Example: Interpolating on health
   class Health {
     public float hp;
     public float maxHp;

     public void set(Health o) {
       set(o.hp, o.maxHp);
     }
     public void set(float hp, float maxHp) {
       this.hp = hp;
       this.maxHp = maxHp;
     }
   }

   class LinearHealthInterpolator implements Interpolator<Health> {
     void interpolate(Health flyweight, Health initialValue, Health currentValue, float alpha) {
       // Note that we're cascading the interpolators to individual fields within the Health component.
       flyweight.hp = Interpolators.linearFloat().interpolate(initialValue.hp, currentValue.hp, alpha);
       flyweight.maxHp = Interpolators.linearFloat().interpolate(initialValue.maxHp, currentValue.maxHp, alpha);
     }
   }

   // Initialize the interpolated health value
   InterpolatedValue<Health> health = new InterpolatedValue<>(new LinearHealthInterpolator(), new Health(), new Health());
   health.getInitialValue().set(10f, 10f);
   Health currentValue = health.getCurrentValue().set(10f, 10f);

   // Update the interpolated health value
   health.getInitialValue().set(health.getCurrentValue()); // before updating the value, the initial value needs to be set
   health.getCurrentValue().hp = 5f; // The current value can be updated any time afterwards

   // Use the interpolated value at 50% the current value
   Health flyweight = new Health();
   health.getInterpolatedValue(flyweight, 0.5f);
   Assert.assertEquals(7.5f, flyweight.hp);
 

Method Summary

Modifier and Type	Method and Description
void	interpolate(T flyweight, T initialValue, T currentValue, float alpha) The interpolation algorithm.

Method Detail

interpolate

void interpolate(T flyweight,
                 T initialValue,
                 T currentValue,
                 float alpha)

The interpolation algorithm. This takes the initial value, the current value, and the ratio of initial value to current value. The result is then stored in the flyweight argument for use.

Parameters:

flyweight - the flyweight value is where the results are stored

initialValue - the initial value

currentValue - the current value

alpha - a value between 0.0f to 1.0f. When alpha is 0.0f, the value should always be the initial value. When alpha is at 1.0f, the value should always be the current value.